Colorants such as pigment preparations are often produced for masterbatches. A masterbatch is a granular, dust-free concentrate of a plastomeric or elastomeric polymer comprising a fraction of a colorant. Masterbatches are used to color plastics, being added to the plastic to be colored prior to or during processing. Masterbatches are used because they provide better colorant dispersion than neat colorant.
A variety of processes for producing masterbatches are known and the following processes are standard in the production of the masterbatches: a) the mixing of a suitable matrix (polymers) with the colorant; b) extrusion and kneading with subsequent grinding of the colorant concentrate; or c) extrusion and subsequent fine spraying, hot chopping, or strand pelletizing.
Known masterbatches generally include a colorant, a dispersant, a thermoplastic polymer, and optionally one or more additives. The thermoplastic polymer is commonly referred to as a “carrier.” A typical commercial formulation of a masterbatch includes about 30% by weight of colorant, about 5% by weight of dispersant, about 10% by weight of additive, and about 55% by weight of a carrier.
Unfortunately, known masterbatches have a relatively low colorant concentration. Thus, it has been found that many known masterbatches have insufficient brilliance for high-quality applications. Larger proportions of colorant cannot be used in known masterbatches due to insufficient dispersion. Insufficient dispersion of the colorant particles can lead to a decrease in physical and mechanical properties of the end product, such as tensile strength, flexural modulus, elongation, and impact strength. Additional problems due to insufficient dispersion include thread breakage during spinning and clogging filters of melt spinning equipment. Accordingly, colorant concentrations have been limited in conventional masterbatches.
Another deficiency in known masterbatch compositions is the inability to include relatively significant amounts of additives such as ultraviolet light absorbers, light stabilizers, antioxidants, and blowing agents. Generally, additives are added only if desired and then in small amounts. Otherwise, it is believed that the processability of the masterbatch would be impaired.
Yet another deficiency in known masterbatch compositions is the inability to significantly improve the processability of the masterbatch itself and of the end product. For example, the melt extrusion of thermoplastics into shaped structures is generally accomplished by well-known procedures such as a reciprocating screw, injection molding, blow molding, compression molding, sheet extrusion, and fiber spinning.
Presently, there is no known system or method for providing a masterbatch composition that avoids the foregoing problems associated with conventional masterbatches. Accordingly, it is desirable to provide a masterbatch composition with improved processability that increases extrusion rates of the masterbatch composition as well as the end product without raising the melt temperature, while producing articles having smoother surfaces, and better physical and mechanical properties than with known masterbatches while reducing the amount of thermoplastic carrier.
It is also desirable to provide a masterbatch composition of colorants and optionally additives that produces better coloration of the end product while reducing the amount of thermoplastic carrier.
The present application, as described and claimed herein, addresses the deficiencies of prior art masterbatches.